Still Bucking, A little less but still noticable Options

[ctc911ctc]

70, 914-6 All stock, original carbs

All Teeners,

In my last Buccee post i took the car for a drive and the carbs were not right though I did balance them using the Least Lean method.

I will leave out that when I dropped the linkage to the carbs that the throttle cable got wrapped around the clutch assembly and what happened next (IMG:style_emoticons/default/mad.gif)

I have been driving the car for the past few days and then I remembered Richard Towles voice telling me it is always dwell, start with the Dwell Grasshopper.

So i went to set the dwell FORGETTING that the Ignition BOX makes dwell angle less relevant (time to charge,etc). BUT, i set it anyway!

Dwell in a 914-6 is done with the Distro OUT of the car
Where is the darn collar bolt located, grrr
Is it an 8 or a 10......sigh its a 10, of course I went in with an 8
pull, Pull, PULL........10 minutes later.......pull, Pull, PULL and POP
Dang, hitting my knuckles when the distro released was painful
Distro on bench, reset (was a tiny bit tight) the gap
Distro back into the car
Where is that hole...........common question from me...... (IMG:style_emoticons/default/dry.gif)
Put the distro back in PUSH, PUSH, ah in......pointing at the wrong angle
Remove distro again - PULLING FOR 10 min.......dang got the other knuckle.
Put the distro back in- angle is good, comutator pointing right at the fan housing...ahh
RATS, did not set TDC prior to removing (IMG:style_emoticons/default/blink.gif)
Removed the distro again. (IMG:style_emoticons/default/sad.gif)
Set car in 5th
Rock forward, never reverse
ah, there it is TDC is white, 35deg is RED (one smart thing I did when Mark sold me the Flywheel - THANK MARK!)
Get the distro into the hole - easier to find with practice (IMG:style_emoticons/default/dry.gif)
get timing light ready
start the car
grind...grind...grind...nothing
Check Electrics
Is the power on the points - yes
Does the ignition box create spark -
pull plug
rock the advance spring - SPARK
Great
Check a dozen things - LIGHT APPEARS OVER MY MARBLE HEAD
180degrees out of phase (IMG:style_emoticons/default/sad.gif)
OK reset TDC,
commutator pointing 180@ out of phase - THE REAL TDC has arrived
PULLLLLLLLLLL out the distro (time 5 and counting)
Rotate
Put back in
set the distro assembly pointed to the fan
Start the car
VrrrRoom! first try.

If you are still here, I was trying to get rid of the bucking when this all began.

Still bucks (IMG:style_emoticons/default/hissyfit.gif)

QUESTION: I will retune the carbs (Stock everything on the carbs) but would you focus on other electric things - wires (new from Pelican), distro is rebuilt (there is a post about it) all new components on distro.

OR

For correct advance testing the 6000RPM advance must be at 35deg....if you adjust this are we not changing the idle advance too? Might the springs be wrong for the timing to be correct at 3000 RPM - bucking is at 2K, 3k and 4k when there is no load either positive or negative.

THANKS in Advance! 35degrees!
CTC

[930cabman]

have you looked at AFR?

[ctc911ctc]

No,

What changes would I consider if sub- optimum in either direction?

Thank you
C

have you looked at AFR?

[TRP]

I think with the AFR, comment above, the thought imight be that if the car is too lean upon acceleration you get a lean pop surge herky jerky motion because the lean mixture burns slower than a properly tuned mixture, etc. etc.

I was dealing with a similar issue on my 4cyl EFI car and chased fuel mixture problems for a few weeks. Only to later discover it was a timing problem because of my A123 distributor was being crazy. (So... yes... totally the opposite situation/set up as you but possible still relevant?) I may be totally off base. Take it for what it's worth.

If you went down the AFR investigation I would start slightly rich to rule out a too lean issue.

The other option is your spark box. How is your voltage to the box? Does it have a low voltage issue that may be causing any disruption to the spark signal? I don't know your setup, just sharing other rabbit holes I went down.

[930cabman]

yes, a bit rich is better than lean

[Superhawk996]

yes, a bit rich is better than lean

Running rich will not solve if the Venturis are too large.

If Venturis are too large you lose air velocity when tipping in under light load cruise conditions. This loss of velocity is the root cause of temporary lean conditions until RPMs and air velocity pick back up.

Running rich will help mask it but it will not solve a Venturi sizing issue.

I keep reading that carbs are stock but after 50 years in the wild, stock carb bodies is not necessarily the same thing as stock Venturis.

[mskala]

Hmm,
based on what I've seen from your engine and your posts about the
distributor, seems like it could still be something bad on the distributor.
If it was only just off the throttle stops, I would think side-to-side carb
linkage adjustment, but that won't explain the higher RPM stuff.
You could try something from my marelli stash if you want.

[ctc911ctc]

Thank Mark - i am going to recal the carbs tomorrow, will let you know!

[porschetub]

Hmm,
based on what I've seen from your engine and your posts about the
distributor, seems like it could still be something bad on the distributor.
If it was only just off the throttle stops, I would think side-to-side carb
linkage adjustment, but that won't explain the higher RPM stuff.
You could try something from my marelli stash if you want.

(IMG:style_emoticons/default/agree.gif) certainly seems like electrical to me ,the OP should take up Marks offer of a replacement (tester ) dizzy, simple to change cap rotor and points for test ,one job off the list to check.
Has the CDI been checked for correct operation ? it should be an early Bosch 3 pin unit and these are known to give issues due to their age ,my point is that you may have a partial miss-fire which could well be your "bucking issue" .
Before proceeding further have you changed the plug leads as you said ? .
Cheers.

[ctc911ctc]

Mark is awesome and has been a terrific source of wisdom. I will follow his lead. I had the ignition box out, it was dirty but seemed to work - the audio test works well (IMG:style_emoticons/default/wink.gif)

I am pursuing electrical - and will be re-tuning the carbs.

Thank you,
CTC

Hmm,
based on what I've seen from your engine and your posts about the
distributor, seems like it could still be something bad on the distributor.
If it was only just off the throttle stops, I would think side-to-side carb
linkage adjustment, but that won't explain the higher RPM stuff.
You could try something from my marelli stash if you want.

(IMG:style_emoticons/default/agree.gif) certainly seems like electrical to me ,the OP should take up Marks offer of a replacement (tester ) dizzy, simple to change cap rotor and points for test ,one job off the list to check.
Has the CDI been checked for correct operation ? it should be an early Bosch 3 pin unit and these are known to give issues due to their age ,my point is that you may have a partial miss-fire which could well be your "bucking issue" .
Before proceeding further have you changed the plug leads as you said ? .
Cheers.

[porschetub]

Just be aware the unit can "buzz" even when faulty ,get your dizzy sorted then move on to the CDI see how you go cheers.